Bug 1035557 - Migrate crash checkpoints with the session so that we don't appear to crash during reset. r=ttaubert, a=sylvestre

(grafted from 07e19701c947cc02fd4b7d76810f57bfeddcb162)

--HG--
extra : source : 07e19701c947cc02fd4b7d76810f57bfeddcb162
extra : amend_source : 82a8b45ebee8af34fa166a38414098172ea45341